Field of the Invention
Disclosed embodiments relate generally to vehicle systems and networks, such as, railway systems including trains travelling in a track or rail network, and in particular to a method and system for providing improved protection for trains operating at restricted speed, such as in connection with positive train control (PTC) systems.
Description of Related Art
Vehicle systems and networks exist throughout the world, and, at any point in time, a multitude of vehicles, such as, cars, trucks, buses, trains, and the like, are travelling throughout the system and network. With reference to trains travelling in a track network, the locomotives of such trains are typically equipped with or operated using train control, communication, and management systems, (e.g., positive train control (PTC) systems), such as, the I-ETMS® of Wabtec Corp.
The Code of Federal Regulations (CFR), Section 49, Part 236, Subpart G-Definitions §236.812, defines restricted speed as “A speed that will permit stopping within one-half the range of vision, but not exceeding 20 miles per hour.” In conventional train management systems, certain train control functions are programmed or configured to limit a train to the objective speed limit, such as a speed limit of 20 mph. However, such existing systems cannot provide protection with respect to other vehicles and/or unmonitored rail obstructions or conditions. In particular, existing PTC systems can enforce the objective portion of this definition, (i.e., 20 mph), but are unable to enforce the subjective (and true intent) of the regulation.
For at least these reasons, there is a need in the art for an improved train control system and method.